Process for extracting gold and silver from ores.



No. 871,766. PATENTED NOV. 19, 1907.

' G. GURNBY. PROCESS FOR EXTRAGTING GOLD AND SILVER PROM ORES.

APPLIUATIONTILED MAY 23, 1904.

GILBERT GURNEY, OF BERKELEY,CALIFORNIA.

PROCESS FOR EXTRACTING GOLD AND SILVER FROM 031138.

Specification of Letters Patent.

Patented Nov. 19, 1907;

Application filed May 23. 1904- Scrial No. 209,370.

To all whom it may concern:

Be it known. that I, GILBERT GURNEY, a subject of Great Britain, residing at Berkoley, in the county f Alameda, State oi -California, have illVGIllm'l a new and useful Improvement in the I iocess of ExtractingGold and Silver 'lrom' Or-s, of which the following is a specification.

My invention relates primarily to the extraction ol gold and silver from sullid ores.

In the methods heretofore practiced for the reduction of such ores it has been. necessary to first roast the same or subject them to some form of calcination or to some other oxidizing process which will eliminate the sullur, requiring much time and cost in the operation.

By my process I obviate the necessity of roasting or calcination in any form, thereby reducing both'time and cost in saving the values from such ores. To put it differently, in my process I take the raw ores and treat them directly with a solution containing the higher or perchlorid of a metal of two or more valencies, and thereafter precipitate the values from the resultant solution. WVherever I use the expression raw ores I mean ores which have not been roasted or subjected to any form of calcination or any oxidizing process.

I have discovered that when a sulfid ore carrying gold. or silver is brought into intimate contact with the higher or perchlorid of a metal of two or more valencies e. g.

ferric chlorid-together with the chloridoil the alkali metals (sodium, potassium, ammonium, etc.,) orof the alkaline earth metals (magnesium, calcium, etc.) the chlorid will give up one chlorin ion, which in turn unites with the metal in. the sulfld ore, forming a chlorid of that n'ietal, (gold or silver as the case may be) from which the values may be easily recovered. l utilize this discovery as the basis of my process.

The accompanying drawing illustrates one form oi. apparatus by which my process may be practiced, in which 1, is a tank wherein. the mass or ore subjected to the action of the solvent liquid I use and heroinal'ter described. This tank is provided with a false bottom 3, arranged to form a chamber below the ore mass.

Numeral i represents the ore; 5 a drain pipe connecting thotnnk l, with a prccipitating vat 6: 7 an electric generator for supplying a current of electricity: 8, the anode which will preferably be of carbon, although the same may be of any substance which will not combine with the chlorin ions, and 9 the cathode disposed in the vat 6: 10-10 wir for conducting the electric current; 3 a pump, and 11 a pipe for returning the liquid by means of the pump from the vat 6 to the tank 1 for re-using after the metals have been precipitated from the solution in vat 6.

Among the sulfid ores some of them carry only silver values, others only old, and still others both silver and gold. W hen silver is present it is in the form of sulfid of'silver, and when gold is present it is in the form of metallic gold, mechanically held by the base sulfids. I shall first describe my processes applied to those sulfids carrying both silver and gold values.

In the tank 1, or any other suitable receptaclc, I place the mass of raw ore to be treated, the same being in a sui'liciently divided state toiree the ore from its gangue or matrix and allow the solution to come into contact with the sulfid. I then prepare a solution consisting of the higher or perchlorid of a metal of two or more valcnc1ese. g. ferric chloridthe chlorid of an alkali metal (sodium, potassium, ammonium, etc.) or the chlorid of an alkaline earth metal (magnesium, calcium, etc.) and a free mineral acid in quantity sul'licient to submerge the mass of ore in the tank 1. In my experiments I have found that the higher or per.- chlorid of any metal of two or more valencies (e. g. ferric, cupric, mercuric, or manganic chlorid) will answer the purpose, chemically, of the first named ingredient, in a more or less degree; but in actualpractice I prefer to use lcrric chlorid on account of its cheapness, and hereinafter I shall describe the process as utilizing ferric chlorid, it being understood that I do not limit myself thereto, but may use any other the higher or pcrchlorid of any other metal oi two or more valcncies.

'lhe alkali metal chlorid I prefer to use as the second ingredient is salt, but .I may use any other alkali metal chlorid or an alkaline earth chlorid; and the acid I prefer as the third ingredient is hydrochhn'ic, but I may use any other mineral acid.

I do not confine myself to any definite proportions of the named ingredients, but in may be employed. The stirrer shown is pivotecl at 15, is adapted to be rotated within the tank by any suitable means, and is provided with two sets of radiating arms 13 and 14, entendmg at right angles from the shaft of the stirrer. Instead of agitating the mass, I may leach it; but agitation is preferable.

The result of this Operation is that the ferric chlorid gives up one chlorin ion, which unites ssh with the gold and silver contained in the ore forming gold and silver chlorids respectively. Thereupon these chlorids are dissolved in the solution, the presence of the alkali metal chlorid bein necessary for dissolving the.- silver ClilOIKT,

'but not for the gold chlorid, which is soluble in water alone. For the sake of brevity, I shall hereinafter use the expression alkali-metal chlorid to cover both the ClllOlldSpf alkali metals and chlorids of alkaline earth metals. The mineral acid usedhastens the action. The ferric chlorid avlng given up one chlorin ion, is converted into ferrous chlorid. The solution carrying the metals Is now drawn off from the tank t rough the pipe 5. into the precipitating vat nd there subjected to an electric current 01 ow density supplied from electric generator 7, through wires 10,l0, whereby the metalsare precipitated'on the cathode, from hich they may be. removed in any. well nown manner. In precipitatingthe metals the electric current releases the chlorin ion from its engagement with the me tal, and this ion immediately recombines with the ferrous chlorid, which is thereby restored to its initial condition of ferric chlorid. As the alkali metal chlorid does not materially deteriorate in the operation, the regenerated solution is now pumped from the precipitating vat back into the tank 1 to be again used on a fresh batch of ore, and it will thus be seen that the process is cyclic.

01" course, where acid is employed, should the solution lose its acidity in use, more may be added to keep up the acid condition.

In order to secure an even deposition of the metal on the cathode l may use in the s..- lution a small amount of gelatin either animal or yegetable, which causes the metals to more iirmly adhere to the cathode.

hen the ore treated essentially a silver sullid alone the use ol the free acid is not osermee sential, though desirable. Then treating ores carrying only gold, the alkali metal chlorid may be dispensed withfin'asmuch as gold chlorid is soluble in water. But when treating ores carrying silver sulfid th'euse of an alkali metal chlorid is necessary as a solvent for the silver chlorid. 3 i I I do not limit my processto sulfid ores; but it may be used to recover'gold or silver when combined with bromin, iodin, chlorin, 7.5 arsenic or tellurium, or other elements.

Having thus described my invention What I claim as new is: I

1'. The process of extracting the Values from sulfid ores, which consists in first subjecting at normal temperatureand Without pressure the raw ores t0 the action of a solar tion containing the higher or perchlorid'of' ,a metal of two or more valencies, together with a chlorid of an alkali metal and'a free mineral acid, and afterwards precipitating the values from the resultant solution.

2. The process of extracting the values from sulfid ores which consists in first subjecting at normal temperature, and'without pressure the raw ores to the action of a solu' tion containing 'terric chlorid, sodium chlo-' rid, and hydrochloric acid, and" afterwards precipitating the values from the resultant solutien'by electrolytic action.

3. The process of extracting the values from sullidores which consists in the following steps: first, submerging the raw ores in a solution containing the higher or perchlorid of a' metal of two or more valencies, together 1 0 with the chlorid of an alkali metal and a free mineral acid; second, agitating. the mass; third, drawing of? the resultant liquid into a precipitating vat; fourth, precipitating the metals in said vat, i

4. The process of extracting the values from sullid ores which consists inthe following steps: first, submerging the raw ores in a solution containing the higher or perchlorid of a metal ol two or more valencies, together with a chlorid of an alkali metal and a free mineral acid; second, agitating the mass; third, drawing oil the resultant liquid into a precipitating vat; fourth, precipitating the metals in said vat by electrolytic action.

5. A cyclic process for treating sullid ores consisting ol the following steps: subjecting the raw ores to the action of a solution containing the higher or rmrclilorid ol a metal of two or more valei'icics, together wiih the chlorid of an alkali metal and a tree mineral acid, whereby the metals in the orcs are converted into chloride; drawing oil the resultant liquid into a precipitating vat; precipitating the metals from llUiY'ClIlOI'illS in said vat, whereby the chlorin ions liberated will rcgci'icrate said higher or pcrchlorid 01 said metal ol two or more valencies; then pumping the rcgcncrahul solution back into the agitating tank tor use on l'resh ores and then continuing the process as already described.

6. The process of extracting gold and silver from sulfitl ores, which consists in treeting the ores with a solution containing the higher or persalt of a metal of two or more valeneies to dissolve the values from the ores, and thereafter subjecting the solution to electrolytic action simultaneously to precipitate the values from the solution and regenerate 10 the protoselt resulting from the first stop in the process lmok to the persalt.

In wituess vhereot l hereunto set my hand this Hill (lay of May A. D. 1904.

' GILBERT GURNEY. W i messes:

J. ll. .llllLI'ADR, S1MP1ON ll. Pm LIPs. 

